Method for whitening teeth

ABSTRACT

A method for whitening teeth which utilizes laser light to activate bleaching agents applied to the teeth. The mouth is first prepared so that the soft tissues of the gums are protected and only the teeth are exposed. The teeth are cleaned to remove any materials which will reduce or nullify the effects of the bleaching agents. A first bleaching composition comprising a peroxide compound is prepared and applied to the teeth. The teeth are exposed to laser light from an argon laser which light activates the peroxide to accelerate the bleaching process without heat. If further whitening is desired, a second bleaching composition comprising a peroxide compound is prepared and applied to the teeth. The teeth are briefly exposed to laser light from a carbon dioxide laser which heat activates the peroxide to accelerate the bleaching process.

This application is a continuation of application Ser. No. 08/708,527,filed Sep. 5, 1996 now U.S. Pat. 5,713,738, which is acontinuation-in-part of application Ser. No. 08/570,901, filed Dec. 12,1995, now U.S. Pat. No. 5,645,428.

FIELD OF THE INVENTION

The present invention relates to a method for whitening teeth. Moreparticularly, the present invention relates to a method for whiteningteeth which utilizes laser light to activate bleaching agents.

BACKGROUND OF THE INVENTION

Development in the field of teeth whitening has led to the presentlyused method of “power bleaching,” which is generally described asfollows. A rubber sheet or dam is placed over the patient's teeth sothat the teeth protrude through the sheet. The dam is made from latexrubber forced over each tooth and held in place with metal springs,clamps, and ligatures. This partially protects the soft tissues of thegums from the peroxides used in bleaching. However, since the rubbersheet stretches and does not custom fit the particular patient's mouth,the peroxide can leak around the rubber sheet and cause substantialdiscomfort to the patient. Typically, this method can be performed onlyon the upper or lower set of teeth at a time, not both.

Once the rubber sheet is in place, a peroxide solution is coated on theteeth. Since the bleaching effects of peroxide are slow, the commonpractice is to apply heat to the peroxide to accelerate the reaction.This is accomplished with the use of a heat lamp or heating iron.Although the heat accelerates the bleaching process, a substantialamount of time is still required so that the entire bleaching processmust be performed over several appointments, resulting in inconvenience,time loss, and substantial expense.

The heat lamp activates the peroxide on a plurality of teethsimultaneously but, due to the amount of heat required where heat is thesole means for activating the peroxide, also exposes the patient's faceto significant amounts of heat, which is quite uncomfortable and cannotbe endured for a prolonged period. While the heating iron does notexpose the patient's face to the same extent as the heat lamp, it takesa much longer time to perform the whitening since it affects only one ortwo teeth at a time. In addition, prolonged exposure to heat willincrease the temperature of the pulp within the tooth, causingdiscomfort to the patient if the pulp temperature gets too high. Sincethe amount of heat commonly used in this type of procedure could killthe pulp and cause tooth loss if exposure is prolonged, continuousexposure must be limited. As a result, 2 to 5 office visits are requiredbefore adequate bleaching is attained.

Other prior art tooth bleaching techniques utilize both light andchemical activation of hydrogen peroxide to accelerate the bleachingprocess. For example, in Toh, C. G. “Clinical Evaluation of aDual-activated Bleaching System,” Asian Journal of Aesthetic Dentistry,Vol.1, No. 2, pp. 65-70 (July 1993), a powder containing potassiumpersulphinate (sold under the name “Oxone” by the DuPont Corp.) wasmixed with solutions of hydrogen peroxide to form a paste. The paste wasapplied to discolored teeth and activated using a dental curing light.Two different concentrations of hydrogen peroxide were used—19% and 35%.A similar process is disclosed in U.S. Pat. No. 5,032,178, which alsomentions the use of a 30-35i% aqueous solution of hydrogen peroxide,with Oxone as an accelerator, and a dental curing light.

The described use of the laser whitening method of the present inventionhas certain advantages over the use of dental curing lamps and the like.For example, heat lamps designed for tooth whitening, such as the UnionBroach Illuminator, utilize halogen bulbs which are significant sourcesof yellow light. However, because the pulp tissue in living teeth isred, it rapidly absorbs the yellow light causing it to rise intemperature, resulting in patient discomfort. A similar problem ariseswith incandescent bulbs. Like halogen bulbs, they produce allwavelengths of visible light, much of which is absorbed by the toothpulp.

Also known in the art is the use of a laser in combination with hydrogenperoxide to bleach teeth. For example, Spanish patent application no. ES528007, in the name of Vicente M. Torres Zaragoza, generally disclosesthe use of laser radiation to accelerate the bleaching action ofhydrogen peroxide, but does not disclose a specific type of laser ormethod of using a laser to accelerate bleaching. Unlike curing lights,lasers permit the practitioner to expose selected teeth to a focusedbeam of light, thereby concentrating the energy of the beam where it isneeded.

From the foregoing it may be seen that there remains a need for a methodof whitening teeth which better protects the soft tissues, shortens thetime for the procedure, and reduces the discomfort to the patient.

In accordance with the principles of the present invention, the use ofthe light source of the described laser permits the practitioner tochoose the specific wavelength of such light that will be most effectivein eliminating the particular stain. It is advantageous to select awavelength close to the color of the stain to be bleached so that thelight will be absorbed primarily by the stain molecules rather than thetooth pulp.

SUMMARY OF THE PRESENT INVENTION

It is the object of the present invention to provide a method forwhitening teeth that improves upon prior art methods and substantiallyreduces discomfort to the patient.

It is another object of the present invention to provide a method whichcan be performed within a short period of time, requiring only oneoffice visit in most cases.

These and other objects of the present invention are accomplishedthrough a method which utilizes laser light from an argon ion laser toactivate bleaching agents applied to the teeth. The mouth is firstprepared so that the soft tissues of the gums are protected and only theteeth are exposed. This is preferably accomplished using wax-like stripsapplied to the gums to isolate the gums from the chemical bleachingcompounds. Typically, prior to a bleaching treatment, the teeth arecleaned to remove any materials which may reduce or nullify the effectsof the bleaching agents. A mixture of peroxide is prepared and appliedto the teeth. The teeth are then exposed to laser light from the argonlaser to light activate the peroxide and accelerate the bleachingprocess.

In alternate embodiments of the invention, “boosters” and catalysts areused to further accelerate the bleaching process. Boosters are chemicalcompounds that, like hydrogen and carbamide peroxide, decompose intofree oxygen radicals and thereby increase the effectiveness of thebleaching compound beyond that of the hydrogen peroxide alone byboosting the free oxygen radical concentration. A catalyst is anysubstance that causes a change in the rate of a chemical reactionwithout itself being consumed by the reaction.

In a preferred method of the present invention, a first bleaching steputilizing peroxide, light activated with an argon laser, is followed bya second bleaching step also utilizing peroxide, heat activated using acarbon dioxide laser.

These and other objects and advantages of the invention will becomeapparent from the following detailed description of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, whitening teeth can beachieved dramatically and quickly using laser energy to activate, i.e.,accelerate the decomposition of, a peroxide solution applied to apatient's teeth. This method of whitening teeth can be performed in oneoffice visit and subjects the patient to minimal discomfort.

Prior to applying a bleaching composition, it is necessary to isolatethe patient's teeth so that only the teeth are exposed and the gumsprotected. This can be done using a rubber dam or sheet as described inprior art bleaching methods. Preferably, however, strips of a wax-like,moldable material having a pressure-sensitive adhesive quality areapplied over the patient's upper and lower gums such that one side ofeach strip overlays the part of the teeth adjacent the gums. This sideof each strip is molded so that it follows the contour of the gumsadjacent the teeth, a process called “festooning.” The strips arecomprised of pectin, sodium carboxymethyl cellulose, gelatin,polyisobutylene, and silicone release paper. In a preferred embodiment,strips sold under the name Stomahesive® strips and manufactured byConvaTec of Princeton, N.J., may be used. The strips are applied byremoving the backing and slightly moistening the strip beforeapplication so that it adheres to the gums. These strips are chosenbecause they will not melt from the heat of a heat lamp or laser. Anyremaining exposed soft tissues of the cheeks or gums are protected withtissue protectants that will break down peroxides, such as non-toxicmetallic or enzymatic solutions created for this purpose, such asBriteSmile Laser Muco-Proe gel available from Ion Laser Technology, Inc.of Salt Lake City, Utah.

Typically, as a precursor to the bleaching process, and to maximize thebleaching effect of the peroxide and ensure complete coverage of theteeth, the front surfaces of the teeth are cleaned to remove anydeposits that may interfere with the bleaching process, such as ironresidues in lipstick, calculus, or plaque. However, this is not arequired step in the process. A preferred cleaning solution contains:approximately 50% purified ethanol, although any concentration between30% and 90% can be used; approximately 10% hydrogen peroxide, althoughany concentration between 0% and 30% can be used; an acid selected fromthe group consisting of phosphoric, citric, hydrochloric, acetic, andhydrofluoric acids; and deionized distilled water. Typically, the finalconcentration of acid is approximately 10%, although any concentrationbetween 3% and 35% can be used. After cleaning, the teeth are rinsedwith deionized distilled water so that no significant contaminantsremain on the front surfaces of the teeth.

Following the cleaning step, the teeth are bleached according to any ofthe embodiments of the present invention disclosed herein. The use oflasers provides several benefits over heat lamps and the like. First, alaser may be chosen with a wavelength tailored to the color of the stainmolecules so that the energy of the laser is largely absorbed by thestain molecules rather than the tooth pulp. Second, lasers provide muchgreater control over the density of the energy applied during thebleaching process by providing a narrow, focused beam of light.

In order to bleach teeth stained with brown and gray stain molecules, anargon ion laser is used to light activate the peroxide. Argon is chosenbecause in the visible spectrum it produces blue and green light with awavelength in the range of 450-530 nanometers. Table 1 illustrates therelative power of the different wavelengths of light produced by a 500mW argon ion laser.

TABLE 1 Wavelength (nm) Power (mW) Spectrum 363.8 and below 0.344Ultraviolet 454.6 0.03 Visible (blue) 457.9 0.06 Visible (blue) 465.80.03 Visible (blue) 472.7 0.05 Visible (blue) 476.5 0.12 Visible (blue)488 0.32 Visible (blue) 496.5 0.12 Visible (blue) 501.7 0.07 Visible(geeen) 514.5 0.40 Visible (green) 528.7 0.07 Visible (green)

As indicated in the table, in addition to the ultraviolet component, theargon laser generates two power spikes, one at 488 nm (blue) and one at514.5 (green). Brown and gray stains absorb blue and green light well,but blood—the primary absorbing pigment in tooth pulp—does not. This isbecause both hemoglobin and oxyhemoglobin have relatively low energyabsorption characteristics for light with wavelengths of 488 and 514.5nm. In addition, unstained tooth enamel is white, which reflects mostenergy, particularly in the visible spectrum. Therefore, the lightenergy of the laser is absorbed primarily by the oxidizing molecules andnot the tooth pulp. This has the advantage of both accelerating thebleaching process by concentrating the light energy where it is neededand minimizing patient discomfort by not significantly raising thetemperature of the tooth pulp. The free oxygen radicals that result fromthe decomposition of, e.g., hydrogen peroxide into water, chemicallyreact with and dechromatize the stain molecules.

In order to avoid overheating the tooth pulp of vital teeth (i.e.,raising the pulp temperature more than 6° C.), the maximum energyapplied to a tooth with an argon laser should not exceed 25 joules perapplication. In a preferred embodiment of the present invention, thetotal energy delivered to each tooth by the argon laser during laserbleaching is approximately 24 joules. This is achieved, for example, bythe use of an argon laser with an output power of 800 mW for 30 secondsper tooth. Higher or lower power lasers may be used, with the exposuretime per tooth adjusted accordingly. As a practical matter, the use ofan argon laser with a power output less than 250 mW may not be feasibledue to the length of exposure time required per tooth. In addition, thelaser may be operated in pulsed mode or continuous wave. In a preferredembodiment, an argon laser with a 7.6 mm spot diameter is used, althoughsmaller or larger beam diameters may also be used. Once all teeth havebeen treated, remaining bleaching mixture is removed from the teeth. Ifneeded, the previous steps of applying the bleaching mixture andactivating with the argon laser can be repeated.

The bleaching mixture may also include a booster to increase the freeoxygen radical concentration and thus accelerate the chemicaldechromatization reaction. A preferred bleaching mixture for use with anargon laser contains an oxygen radical generating agent such as aperoxide, a booster, a desensitizing and color stabilizing agent, athickening agent, and a buffer for maintaining a desired pH range.

A preferred peroxide is hydrogen peroxide, although any peroxide may beselected from the group consisting of hydrogen peroxide, carbamideperoxide, calcium carbonate peroxide, sodium carbonate peroxide, andother oxygen radical generating agents. A liquid solution of hydrogenperoxide is used in the bleaching mixture. A preferred concentration ofhydrogen peroxide in solution for use in the mixture is 35-50%, althoughany concentration between 3% and 50% can be used. The higher theconcentration of peroxide, the greater the bleaching effect. The boosteris preferably selected from the group consisting of ammonium persulfate,sodium persulfate, and potassium persulfate and has a finalconcentration in the mixture of 30%, although concentrations between 1%and 80% are effective. These compounds are used because they areparticularly sensitive to light, i.e., they decompose at an acceleratedrate when exposed to light from an argon laser, releasing free oxygenradicals in the process.

The desensitizing and color stabilizing agent is selected from the groupconsisting of fluoride, calcium, and phosphate, and is used at a finalconcentration in the mixture of 1% for fluoride, 5% for calcium, or 2%for phosphorus, although a concentration between 0.1% and 10% can beused for any of these substances. The thickening agent is selected fromthe group consisting of silicates, hydroxyethylceliulose, lanolate,palnitate, oleate, sodium lauryl sulfate, sodium stearate, calciumstearate, and other fatty acids. The use of sodium silicate has beenfound beneficial because it has an affinity for iron and other heavymetals, and thus helps to prevent them from breaking down the peroxideinto molecular oxygen, which does not provide nearly the same bleachingeffect as the desired free oxygen radicals. Typically, the thickeningagents are used at a final concentration of 5%, although anyconcentration between 1% and 20% can be used. The buffer is selectedfrom the group consisting of urea, sodium carbonate, sodium bicarbonate,calcium carbonate, calcium bicarbonate, ammonium hydroxide, and calciumhydroxide, although any buffering agent can be used. The concentrationof the buffer will depend on what is necessary to maintain a pH between7 and 11 because the peroxide decomposes more rapidly the higher the pH,although the optimal pH is between 7.8 and 9. Once mixed, a 1 to 2millimeter layer of the bleaching mixture is applied to the frontsurface of the patient's teeth.

In order to further accelerate the bleaching process, additional stepsmay be employed. First, in order to thermally agitate and increasediffusion of the peroxide, an infrared heat lamp may be used inconjunction with the laser. Although, for the reasons discussed above,such a lamp is not preferred as the primary means of activation of theperoxide, it is useful as an adjunct to the argon laser to maintain theteeth at a slightly elevated temperature (100-104° F.) to effect thediffusion of the peroxide into the teeth.

Second, a pigment may be added to the bleaching composition to furtherincrease the amount of light energy absorbed by the oxidizing molecules.For example, if a yellow pigment is added to the composition, it willabsorb the blue and green light from an argon laser but substantiallyreflect yellow light generated by the infrared lamp. Because the pulp inlive teeth is red, yellow light is absorbed by the pulp, causing painand inflammation if the pulp gets too hot. Thus, the use of a yellowpigment also acts to prevent harm to the teeth by helping to lower thepulp temperature during bleaching. In a preferred embodiment, FD&Cyellow 5 LAKE or 6 LAKE is used as the pigment. Similarly, a red ororange pigment may be used in conjunction with the argon laser. The redor orange pigment will also help the bleaching mixture absorb blue,green and yellow light, and reflect any red or orange light.

As an additional step to enhance the effectiveness of the process, theteeth may be subjected to a preconditioning step prior to the laseractivated bleaching step, as follows. An additional coat of bleachingmixture, as described above, is applied to the teeth and allowed toremain in the teeth for a period sufficient to permit the mixture tosoak into the teeth. This step helps to clean the teeth and soak themwith peroxide in advance of the argon laser bleaching step. Typically, aperiod of about 30 minutes is adequate, although a period between 15 and60 minutes may be used. This mixture is removed and a fresh mixtureplaced on the teeth for the laser activation step described above. Ithas been found that this preconditioning step improves the whiteningeffect of the subsequent laser activated bleaching step.

The use of an argon laser in conjunction with a peroxide bleachingcomposition may be sufficient to achieve the desired shade of whitenessin many patients in a single office visit. However, while an argon laseris effective for whitening teeth with brown and gray stains because ofthe blue light generated, its effectiveness decreases as the teethbecome whiter. This is because as the light absorbing stains aredechromatized, more of the blue and green light from the argon laser isreflected. Therefore, as a second bleaching step, an infrared lightgenerating laser may be used in conjunction with a free oxygen radicalgenerating composition to further whiten teeth that have already beentreated with an argon laser. In a preferred embodiment, a carbon dioxide(CO₂) laser is used. The infrared energy increases the temperature ofthe hydrogen peroxide, thus accelerating its decomposition into waterand a free oxygen radical. The infrared energy is quickly absorbed bythe hydrogen peroxide and water present on the surface of the toothenamel during the bleaching process. In addition, the nonliving toothenamel acts as a heat sink to protect the living parts of the teeth fromthe energy of the laser. Thus, for lightly stained teeth, such as inteeth stained with tanic acid, an infrared laser is more effective thanan argon laser because the infrared energy interacts directly with thehydrogen peroxide.

A carbon dioxide laser is preferred for this step because it generateslong wave infrared energy (10-11 micron wavelength), which is absorbedwell by water. Thus, as the peroxide decomposes to water and a freeoxygen radical, the water absorbs the infrared energy generated by thelaser and is vaporized, thereby heat-activating any remaining peroxide.In order to avoid overheating the tooth pulp while using the carbondioxide laser (i.e., raising the pulp temperature more than 6° C.), themaximum energy imparted to a tooth with a carbon dioxide laser shouldnot exceed 15 joules. In a preferred embodiment, a total of 12.5 joulesof energy is applied to each tooth during an application. This isachieved, e.g., by the use of a carbon dioxide laser with a 2.5 W poweroutput for a period of 5 seconds per tooth. Higher and lower poweroutputs may be used, with the exposure time adjusted accordingly. Inaddition, the laser may be operated in pulsed mode or continuous wave.In a preferred embodiment, a carbon dioxide laser with a 3 mm spot beamis used. Once all teeth have been treated, any remaining bleachingmixture is removed from the teeth. If needed, the previous steps ofapplying the bleaching mixture and activating with the carbon dioxidelaser may be repeated.

Although a CO₂ laser is preferred, other infrared lasers can be used.For example, an Neodymiun (Nd) Yttrium Arsenic Gallium (YAG) laser mayalso be used. However, Nd:YAG lasers have detrimental side effects dueto the fact that they generate energy of a shorter wavelength than CO₂lasers. The energy generated by an ND:YAG laser penetrates through toothenamel more effectively than a CO₂ laser and is absorbed by the toothpulp, resulting in a higher pulp temperature.

A catalyst and/or booster may also be used in conjunction with a CO₂laser to further accelerate the bleaching process. One example of abooster is sodium perborate, which decomposes into peroxide to provideadditional free oxygen radicals, thereby effectively increasing theconcentration of the peroxide. Sodium perborate is preferable for usewith the carbon dioxide laser, because its decomposition is acceleratedby heat more so than light, as compared with the boosters that are usedwith the argon laser. Other compounds, such as sodium carbonate, sodiumbicarbonate, calcium carbonate, ammonium hydroxide, sodium hydroxide,potassium hydroxide, and calcium hydroxide, act to raise the pH of thebleaching mixture so as to accelerate bleaching.

A preferred bleaching mixture for use with a CO₂ laser contains anoxygen radical generating agent such as a peroxide, a catalyst, adesensitizing and color stabilizing agent, a thickening agent, and abuffer for maintaining a desired pH range. The peroxide, thedesensitizing and color stabilizing agent, the thickening agent, and thebuffer and pH range may be the same as the first bleaching mixture.Typically, the catalyst or booster is used at a final concentration of30%, although any concentration between 3% and 80% can be used. Oncemixed, a 1 to 2 millimeter layer of the bleaching mixture is applied tothe front surface of the patient's teeth.

Some of the foregoing catalysts, such as sodium carbonate and sodiumbicarbonate, are also used as buffers. In addition to their pH raisingeffect, these compounds also act as catalysts due to their hydrophiliceffect. In water, ions are surrounded by a layer of water molecules,called a primary hydration sphere. As the water molecules form thisprimary sphere surround the ions, their polarity is oriented to exert anenhanced hydrogen-bonding attraction on other water molecules. Thisresults in formation of a secondary hydration layer around the firstlayer. Subsequent hydration layers can also form, depending on the sizeand charge of the ions. As water molecules are pulled into thesehydration layers, the effective concentration of the oxygen radicalgenerating agent is increased, resulting in greater instability and afaster rate of reaction.

For approximately 72 hours following the whitening of the teeth usingthe aforedescribed laser bleaching process, the teeth are generally moresusceptible to staining because they are dehydrated. In order to preventstaining during this period and stabilize the color change, it isadvantageous to provide patients with an in-home bleaching kit,comprising an 8-10% peroxide solution in a gel and either a custom madevacuum-formed mouth guard or disposable foam tray. Typically, the trayis worn for at least 15-30 minutes a day for 3-10 days following thelaser bleaching procedure, depending on the patient.

It is to be understood that the method of the invention disclosed is apreferred embodiment thereof and that various changes and modificationsmay be made therein without departing from the spirit of the inventionor scope as defined in the following claims.

I claim:
 1. A method for whitening a patient's teeth comprising thesteps of: preparing a bleaching composition comprising an oxygen radicalgenerating agent and a substance for raising the pH of said bleachingcomposition; applying said composition to said teeth; and exposing eachof said teeth to laser light from an argon laser for a selected timeinterval to accelerate whitening.
 2. A method as described in claim 1,wherein said oxygen radical generating agent is selected from theperoxide group consisting of hydrogen peroxide, carbamide peroxide,calcium carbonate peroxide, and sodium carbonate peroxide.
 3. A methodas described in claim 2, wherein said argon laser has a wavelength rangein the visible spectrum between approximately 450 and 530 nanometers andeach tooth to be treated is exposed to approximately 24 joules of energyfrom said argon laser.
 4. A method as described in claim 1, wherein saidpH-raising substance is sodium hydroxide.
 5. A method as described inclaim 1, wherein said pH-raising substance is potassium hydroxide.
 6. Amethod as described in claim 1, wherein said pH-raising substance iscalcium hydroxide.
 7. A method as described in claim 1, wherein saidpH-raising substance is ammonium hydroxide.
 8. A method as described inclaim 1, wherein said pH-raising substance is selected from the groupconsisting of sodium carbonate, sodium bicarbonate, and calciumcarbonate.
 9. A method as described in claim 1, wherein said compositionfurther comprises: a desensitizing and color stabilizing agent selectedfrom the group consisting of fluoride, calcium, and phosphate andproviding a concentration of said desensitizing and color stabilizingagent in said mixture between 0.1% and 10%.
 10. A method as described inclaim 1, wherein said argon laser has a wavelength range in the visiblespectrum between approximately 450 and 530 nanometers and each tooth tobe treated is exposed to approximately 24 joules of energy from saidargon laser.
 11. A method as in claim 1, wherein said bleachingcomposition further comprises a yellow pigment.
 12. A method asdescribed in claim 1, further comprising: preparing a second bleachingcomposition comprising an oxygen radical generating agent; applying saidsecond composition to said isolated teeth; and exposing said teeth tolaser light from a carbon dioxide laser for a selected time interval toaccelerate whitening.
 13. A method as in claim 1 wherein said timeinterval is selected to provide a total of approximately 24 joules toeach of said isolated teeth.
 14. A method as in claim 1 wherein, priorto said exposing step, said composition is removed after a period of15-60 minutes and replaced with additional composition.
 15. A method asin claim 1 further comprising applying an 8-10% peroxide solution tosaid teeth for at least 15-30 minutes a day for a period of 3-10 daysfollowing said exposing step.
 16. A method for whitening a patient'steeth comprising the steps of: isolating the teeth to be treated;preparing a bleaching composition comprising an oxygen radicalgenerating agent and a substance for raising the pH of said bleachingcomposition; applying said composition to said isolated teeth; andexposing each of said isolated teeth to laser light for a selected timeinterval to accelerate whitening.
 17. A method as described in claim 16,wherein said oxygen radical generating agent is selected from theperoxide group consisting of hydrogen peroxide, carbamide peroxide,calcium carbonate peroxide, and sodium carbonate peroxide.
 18. A methodas described in claim 16, wherein said pH-raising substance is sodiumhydroxide.
 19. A method as described in claim 16, wherein saidpH-raising substance is potassium hydroxide.
 20. A method as describedin claim 16, wherein said pH-raising substance is calcium hydroxide. 21.A method as described in claim 16, wherein said pH-raising substance isammonium hydroxide.
 22. A method as described in claim 16, wherein saidpH-raising substance is selected from the group consisting of sodiumcarbonate, sodium bicarbonate, and calcium carbonate.
 23. A method asdescribed in claim 16, wherein said laser is a carbon dioxide laser. 24.A method for whitening a patient's teeth comprising the steps of:preparing a bleaching composition comprising a peroxide selected fromthe group consisting of hydrogen peroxide, carbamide peroxide, calciumcarbonate peroxide, and sodium carbonate peroxide, and a substance forraising the pH of said bleaching composition to a pH betweenapproximately 7 and 11; applying said composition to said teeth; andexposing each of said teeth to laser light from an argon laser for aselected time interval to accelerate whitening.
 25. A method asdescribed in claim 24, wherein said pH-raising substance is sodiumhydroxide.
 26. A method as described in claim 24, wherein saidpH-raising substance is potassium hydroxide.
 27. A method as describedin claim 24, wherein said pH-raising substance is calcium hydroxide. 28.A method as described in claim 24, wherein said pH-raising substance isammonium hydroxide.
 29. A method as described in claim 24, wherein saidpH-raising substance is selected from the group consisting of sodiumcarbonate, sodium bicarbonate, and calcium carbonate.